140 INVERTEBRATA OF MASSACHUSETTS. 



obtuse and marginal, the surface covered with minute, concave, 

 or prickly scales, arranged in radiating, undulated lines ; lower 

 valve very thin, smooth, or with a few prickles near the margin ; 

 aperture nearly circular ; within shining ; the convex valve ex- 

 hibiting the exterior ribs near the margin. Diameter about half 

 an inch. 



Found amid the roots of fuci which are thrown up attached to 

 stones, shells^ &c. 



This shell is easily distinguished from its co-species by the scaly or 

 prickly radiating lines upon its upper valve. It seems never to attain 

 a large size. 



Besides the two species before mentioned, there are probably two 

 others found in this State. But all species are so distorted as to ren- 

 der it difficult to separate them definitely. 



1. Anomia electeica, Lin.— distinguished by its sulphur or golden 

 hue, defined edge, and very convex upper valve. It is generally much 

 distorted, transparent, and not so fragile as most species, not scaly. 



Found among oysters. 



2. Anomia squa'mula, Lin. — a small, smooth, rounded, or oblong- 

 oval shell, very thin and regular, exhibiting regular concentric lines of 

 growth ; color whitish ; edges well defined ; aperture rounded. 



Found attached within old bivalve shells. 



These two species, however, are not positively made out. 



Family BRACHIOPODA, Lam. 



Shell adhering to marine bodies either directli/ or by means of a tendinous 

 cord ; animal having a pair of fringed arms, spiraUi/ coiled ivhen at, rest. 



Instead of being regarded as a family of the Conchifera, 

 according to the arrangement of Lamarck, the Brachiopoda are 

 fully entitled to be ranked as a class. The animals are as distinct 

 and peculiar in their organization, as the Cirripedes are. In- 

 stead of the back of the animal being placed against the hinge, as 

 in other bivalves, and the sides against each of the valves, in 

 these we have the back against one valve, and the belly against 

 the other. The pair of long arms, with curled fringe at their 

 edges, is found in no other mollusca. 



